Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS5279293 A
Publication typeGrant
Application numberUS 07/861,150
Publication dateJan 18, 1994
Filing dateMar 31, 1992
Priority dateApr 9, 1991
Fee statusPaid
Also published asDE4111478A1, EP0508326A2, EP0508326A3, EP0508326B1
Publication number07861150, 861150, US 5279293 A, US 5279293A, US-A-5279293, US5279293 A, US5279293A
InventorsHans Andersen, Martin Obel, Lars Wallen
Original AssigneeSiemens Aktiengesellschaft
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Implantable defibrillator with fibrillation-inducing capability and method for inducing fibrillation
US 5279293 A
Abstract
An implantable defibrillator has a capacitor which, through a controllable switch arrangement, can either be connected to a voltage source for charging the capacitor, or connected across electrodes placed at the heart for delivering a defibrillation pulse. To calculate the minimum pulse energy required for successful defibrillation, ventricular fibrillation is first induced, so that a plurality of defibrillation attempts, with energy increasing from attempt-to-attempt can be undertaken until successful defibrillation occurs. For inducing ventricular fibrillation, the capacitor of the implantable defibrillator is connected to the voltage source until a prescribed charging voltage, which is significantly below the voltage necessary for defibrillation, is reached, and subsequently, the capacitor is disconnected from the voltage source during brief time spans at intervals within the framework of a sequence and is connected during those time spans to the electrodes. Between the time spans, the capacitor is again charged.
Images(1)
Previous page
Next page
Claims(12)
We claim as our invention:
1. An implantable defibrillator comprising:
a capacitor;
a voltage source;
electrode means for delivering electrical energy in vivo to a heart;
switch means for connecting said capacitor either across said voltage source or across said electrode means; and
control means for operating said switch means to connect said capacitor across said voltage source until said capacitor is charged to a voltage for defibrillation of said heart and, at selected times, to artificially induce ventricular fibrillation in said heart by connecting said capacitor across said voltage source until said capacitor is charged to a prescribed charging voltage which is significantly below said voltage for defibrillation and thereafter disconnecting said capacitor from said voltage source and connecting said capacitor across said electrode means during a plurality of spaced time intervals in a sequence.
2. An implantable defibrillator as claimed in claim 1 wherein said control means operates said switch means connecting said capacitor across said electrode means for time intervals of approximately 8 ms.
3. An implantable defibrillator as claimed in claim 1 wherein said control means operates said switch means connecting said capacitor across said voltage source between said time intervals for respective durations of approximately 25 ms.
4. An implantable defibrillator as claimed in claim 1 further comprising means for directly measuring the voltage across said capacitor for identifying when said prescribed charging voltage is reached.
5. An implantable defibrillator as claimed in claim 1 wherein said capacitor is charged by said voltage source with a prescribed charging current, and further comprising means for defining when said prescribed charging voltage is reached by measuring the expiration of a prescribed time following a beginning of charging of said capacitor.
6. An implantable defibrillator as claimed in claim 5 further comprising means for varying said charging current at least during said sequence.
7. A method for in vivo delivery of electrical energy to the heart, said method comprising the steps of:
implanting a defibrillator and electrodes in a patient, said defibrillator containing a voltage source and a capacitor;
disposing said electrodes relative to said heart for in vivo delivery of electrical energy from said defibrillator to said heart;
connecting said capacitor across said voltage source until said capacitor reaches a voltage for defibrillation of said heart and, in the event of fibrillation discharging said capacitor across said electrodes;
connecting said capacitor to a voltage source until said capacitor reaches a prescribed charging voltage which is significantly below said voltage for defibrillation for inducing fibrillation in said heart at selected times;
after reaching said prescribed charging voltage, disconnecting said capacitor from said voltage source and connecting said capacitor across said electrodes for a plurality of spaced time intervals in a sequence; and
re-connecting said capacitor across said voltage source between said time intervals for charging said capacitor.
8. A method as claimed in claim 7 wherein the step of connecting said capacitor across said electrodes for a plurality of spaced time intervals is further defined by connecting said capacitor across said electrodes for a plurality of spaced time intervals each lasting approximately 8 ms.
9. A method as claimed in claim 7 wherein the step of re-connecting said capacitor across said voltage source for charging said capacitor between said time intervals is further defined by re-connecting said capacitor across said voltage source for a time lasting approximately 25 ms between each of said time intervals.
10. A method as claimed in claim 7 comprising the additional step of:
directly measuring the voltage across said capacitor for identifying when said prescribed charging voltage is reached.
11. A method as claimed in claim 7 wherein the step of connecting said capacitor across said voltage source for charging said capacitor is further defined by charging said capacitor with a prescribed charging current, and comprising the additional step of measuring the expiration of prescribed time following a beginning of charging of said capacitor for defining when said prescribed charging voltage is reached.
12. A method as claimed in claim 11 comprising the additional step of varying said charging current for said capacitor at least during said sequence.
Description
BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to an implantable defibrillator of the type having a capacitor which is connectable via a controllable switch arrangement to a voltage source for charging or to electrodes placed at the heart for delivery of defibrillation pulses thereto, and to a method for inducing fibrillation using such a defibrillator.

2. Description of the Prior Art

In known implantable defibrillators, a capacitor connected within the implantable defibrillator housing or capsule, is charged to a high voltage via a voltage source, also in the housing, and is subsequently discharged through electrodes arranged at the heart and via the heart tissue lying between the electrodes, upon the detection of ventricular fibrillation. A controllable switch arrangement normally connects the capacitor across a voltage source for charging the capacitor, and alternatively connects the capacitor across the electrodes when defibrillation is necessary. When the current flowing across the heart has sufficient energy, ventricular fibrillation is thereby terminated.

In order to identify the minimum amount of energy which is sufficient to achieve a successful defibrillation, it is known to induce ventricular fibrillation artificially, and subsequently to implement a series of defibrillation attempts with increasing energy until the ventricular fibrillation is successfully terminated. For example, ventricular fibrillation can be induced by externally charging the patient with a 50 Hz alternating current from an external generator. It is possible to artificially produce ventricular fibrillation by generating a suitable stimulation pulse sequence by means of a heart pacemaker, which may be implanted either separately from the implantable defibrillator, or in combination with the defibrillator in a common housing.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an implantable defibrillator of the type having a capacitor connectable via a controllable switch arrangement either to a voltage source for charging, or to electrodes for delivery of pulses to the heart, by means of which fibrillation can be artificially induced in the heart in a simple manner.

It is a further object of the present invention to provide a method for artificially inducing fibrillation using an implantable defibrillator of this type.

The above objects are achieved in accordance with the principles of the present invention in a defibrillator of the type described above, including means for operating the switch arrangement for connecting the capacitor across the voltage source until a prescribed charging voltage is reached, which is significantly below the voltage provided for defibrillation, and thereafter, once the charging voltage is reached, for disconnecting the capacitor from the voltage source and connecting the capacitors across the electrodes during a series of brief time spans, which follow each other at intervals within the frame work of a sequence. During the intervals between the time spans, the capacitor is again connected to the voltage source for charging. Ventricular fibrillation can thus be produced using the implantable defibrillator, without the necessity of providing a pulse generator specifically for that purpose, and also without the necessity of providing special electrodes. Instead, the defibrillator disclosed herein generates the pulse sequence required for inducing ventricular fibrillation with the components which are already provided in the defibrillator for defibrillation purposes.

Moreover, because the electrodes, normally used to effect defibrillation are usually large-area electrodes, the pulses which are delivered for the purpose of inducing fibrillation can be limited to a relatively low value, so that damage to the heart tissue is avoided while still reliably inducing ventricular fibrillation. For example, the amplitude of the fibrillation-inducing pulses can be approximately 23 volts, which is significantly below the voltage normally provided for defibrillation. The duration of the time spans which define the pulse duration is preferably on the order of magnitude of 8 ms, and the duration of the interval between pulses is preferably on the order of magnitude of 25 ms.

The voltage amplitude of the pulses can be set by directly measuring the voltage across the capacitor to identify when the prescribed charging voltage is reached.

Alternatively, in a preferred embodiment, the capacitor is charged with a prescribed charging current by the voltage source, and the prescribed charging voltage is defined by the expiration of a given time after the beginning of the charging event.

In a preferred embodiment of the invention, the charging current for the capacitor is variable, at least for duration of the fibrillation-inducing sequence, so that pulse sequences having a steady increase or decrease in the pulse height (amplitude) of the individual pulses can be generated.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block circuit diagram of a preferred exemplary embodiment of a defibrillator constructed in accordance with the principles of the present invention.

FIG. 2 is a graph showing an example of the pulse sequence generated by the defibrillator shown in FIG. 1 for inducing ventricular fibrillation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An exemplary embodiment of an implantable defibrillator is shown in FIG. 1, having a capacitor 1 connectable either to a voltage source 4 or to terminals 5 and 6. The capacitor is connected across either the voltage source 4 or the terminals 4 and 5 by means of a switch arrangement 3 operated by a control unit 2. Respective implantable leads 7 and 8 are connected to the terminals 5 and 6, the leads 7 and 8 respectively terminating in electrodes 10 and 11 which are arranged directly at the heart 9. The capacitor 1, the control unit 2, the switch arrangement 3, the voltage source 4 and a telemetry unit 12 are contained in an implantable capsule housing 13. The telemetry unit 12 is connected to the control unit 2 and to the voltage source 4 for communication with an external programming device (not shown) in a known manner. The electrode terminals 5 and 6 are feedthroughs which extend through the wall of the capsule housing 13, while still permitting the interior of the capsule housing 13 to remain hermetically sealed.

When spontaneous fibrillation of the heart 9 is detected by any of a number of known techniques, the capacitor 1 is connected to the voltage source 4 via the controllable switch arrangement 3 and is charged to a high voltage. The capacitor 1 is subsequently connected by the controllable switch arrangement 3 to the electrode terminals 5 and 6, and the capacitor 1 is discharged through the electrodes 10 and 11 and the heart tissue lying therebetween, and thus effects defibrillation if the discharge current has a sufficient amount of energy. It is therefore necessary in conjunction with the implantation of the defibrillator to identify the lowest amount of energy which will suffice for successful defibrillation. To that end, ventricular fibrillation is artificially induced in the heart 9, and a plurality of defibrillation attempts are subsequently undertaken, each attempt being with a higher energy level until successful defibrillation of the heart 9 occurs. Inducing ventricular fibrillation using the defibrillator constructed in accordance with the principles of the present invention is described in detail below with reference to FIG. 2.

As shown in FIG. 2, the capacitor 1 is connected at a time tO, to the voltage source 4 via the controllable switch arrangement 3, and is charged with the voltage curve referenced 14. The voltage across the capacitor 1, i.e., the charging voltage, is referenced Uc. Upon reaching a prescribed charging voltage UO the capacitor 1 is disconnected from the voltage source for by the controllable switch arrangement 3. The prescribed charging voltage UO can be identified either by measuring the voltage Uc across the capacitor 1 or, in the case of a given charging current, by the expiration of a prescribed time t1 following the beginning of the charging event at t0.

When the prescribed charging voltage Vo is reached, the controllable switch arrangement 3 is operated to connect the capacitor 1 across the electrode terminals 5 and 6 for a brief time span TA. During this time span TA, the capacitor 1 is discharged so as to generate an output pulse 15 across the heart tissue lying between the electrodes 10 and 11. At the end of the time span TA, the capacitor 1 is again connected by the switch arrangement 3 to the voltage source 4, and is charged in accord with the voltage curve referenced 16 during an interval TB. At the end of the interval TB, the capacitor 1 is again discharged across the heart tissue 9 for a time span TA. This procedure is repeated over a sequence consisting of a plurality of pulses 15, 17, 18 and 19, resulting in the artificial inducement of ventricular fibrillation. By varying the charging current, i.e., by varying the slope of the voltage curves 14 and 16 in FIG. 2, sequences having continuously rising or decreasing pulse heights can be generated without altering the interval TB.

Although modifications and changes may be suggested by those skilled in the art it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3602229 *Aug 26, 1968Aug 31, 1971Jaros George GustavA method of fibrillating a heart and apparatus therefor
US4300567 *Feb 11, 1980Nov 17, 1981Mieczyslaw MirowskiMethod and apparatus for effecting automatic ventricular defibrillation and/or demand cardioversion through the means of an implanted automatic defibrillator
US4494544 *Oct 15, 1980Jan 22, 1985Honeywell Inc.Relay for a heart defibrillator
US4996984 *Sep 26, 1989Mar 5, 1991Eli Lilly And CompanyDefibrillation method
US5105809 *Aug 23, 1990Apr 21, 1992Cardiac Pacemakers, Inc.System and method for evaluating lead defibrillation requirements of an implanted device without repeated fibrillation induction
US5111816 *Oct 22, 1990May 12, 1992VentritexSystem configuration for combined defibrillator/pacemaker
US5129392 *Dec 20, 1990Jul 14, 1992Medtronic, Inc.Apparatus for automatically inducing fibrillation
DE1927667A1 *May 30, 1969Dec 3, 1970South Afriean Inv S Dev CorpFibrillator zur Stimulierung von Muskelfasern,Geweben od.dgl.
DE2811325A1 *Mar 16, 1978Sep 27, 1979Messerschmitt Boelkow BlohmFibrillator fuer herzchirurgie
DE3910741A1 *Apr 3, 1989Oct 4, 1990Mela Gmbh ElektromedizinHigh-voltage relay circuit
DE3919498A1 *Jun 15, 1989Jan 11, 1990Atesys SaDefibrillator zur therapeutischen behandlung des herzens
DE4030306A1 *Sep 25, 1990Apr 4, 1991Lilly Co EliDefibrillationsverfahren und vorrichtung
EP0392099A1 *Apr 10, 1989Oct 17, 1990Bernard L. CharmsDefibrillation apparatus
Non-Patent Citations
Reference
1"Ventricular Fibrillation Threshold in the Dog Determined with Defibrillating Paddles," Ruiz et al., Med. & Biol. Eng. & Comput., May 1985, pp. 281-284.
2 *J ros et al., New Approaches to Fibrillation and Defibrillation of the Heart, S. A. Medical Journal, 22 Jan. 1972, pp. 63 67.
3Jaros et al., "New Approaches to Fibrillation and Defibrillation of the Heart," S. A. Medical Journal, 22 Jan. 1972, pp. 63-67.
4Levy et al., "Cardiac Fibrillation-Defibrillation: Use of Electrical Current in Conversion of Cardiac Rhythm-Methods and Results", Am. Journal of Med. Elec. Oct.-Dec. '64.
5 *Levy et al., Cardiac Fibrillation Defibrillation: Use of Electrical Current in Conversion of Cardiac Rhythm Methods and Results , Am. Journal of Med. Elec. Oct. Dec. 64.
6Starmer et al., "Current Density and Electrically Induced Fibrillation," Medical Instrumentation, vol. 7, No. 1, Jan.-Feb. 1973.
7 *Starmer et al., Current Density and Electrically Induced Fibrillation, Medical Instrumentation, vol. 7, No. 1, Jan. Feb. 1973.
8 *Ventricular Fibrillation Threshold in the Dog Determined with Defibrillating Paddles, Ruiz et al., Med. & Biol. Eng. & Comput., May 1985, pp. 281 284.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5395373 *Jan 7, 1993Mar 7, 1995Incontrol, Inc.Atrial defibrillator and method for setting energy threshold values
US5591211 *Dec 9, 1994Jan 7, 1997Ventritex, Inc.Defibrillator having redundant switchable high voltage capacitors
US5609618 *Dec 6, 1995Mar 11, 1997Ventritex, Inc.Apparatus and method for inducing fibrillation
US5643323 *Jun 7, 1995Jul 1, 1997Angeion CorporationSystem and method inducing fibrillation using an implantable defibrillator
US5649971 *Dec 6, 1995Jul 22, 1997Ventritex, Inc.Apparatus and method for inducing fibrillation
US5653740 *Jan 16, 1996Aug 5, 1997Medtronic, Inc.Method and apparatus for induction of fibrillation
US5709711 *Aug 13, 1996Jan 20, 1998Pacesetter, Inc.Implantable defibrillator with electrophysiologic testing capabilities
US5824018 *May 3, 1996Oct 20, 1998Cardiac Pacemakers, Inc.Fibrillation induction method and system for implantable devices
US6016442 *Mar 25, 1998Jan 18, 2000Cardiac Pacemakers, Inc.System for displaying cardiac arrhythmia data
US6091990 *Nov 3, 1999Jul 18, 2000Cardiac Pacemakers, Inc.System for grouping and displaying cardiac arrhythmia data
US6253102May 11, 2000Jun 26, 2001Cardiac Pacemakers, Inc.System for displaying cardiac arrhythmia data
US6301503Sep 29, 2000Oct 9, 2001Cardiac Pacemakers, Inc.System for grouping and displaying cardiac arrhythmia data
US6453201Dec 28, 1999Sep 17, 2002Cardiac Pacemakers, Inc.Implantable medical device with voice responding and recording capacity
US6843801Apr 8, 2002Jan 18, 2005Cardiac Pacemakers, Inc.Method and system for identifying and displaying groups of cardiac arrhythmic episodes
US6865424Aug 8, 2002Mar 8, 2005Cardiac Pacemakers, Inc.Implantable medical device with voice responding and recording capacity
US6987998Feb 28, 2001Jan 17, 2006Cardiac Pacemakers, Inc.Cardiac rhythm management patient report
US7047065Oct 16, 2003May 16, 2006Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US7149575 *May 17, 2002Dec 12, 2006Cameron Health, Inc.Subcutaneous cardiac stimulator device having an anteriorly positioned electrode
US7181275Dec 23, 2003Feb 20, 2007Medtronic, Inc.Method and apparatus for actively determining a coupling interval corresponding to a cardiac vulnerable zone
US7349736Nov 1, 2006Mar 25, 2008Cameron Health, Inc.Active housing dual lead assembly
US7418295Dec 22, 2004Aug 26, 2008Cardiac Pacemakers, Inc.Method and system for identifying and displaying groups of cardiac arrhythmic episodes
US7555338 *Apr 26, 2005Jun 30, 2009Cameron Health, Inc.Methods and implantable devices for inducing fibrillation by alternating constant current
US7751892May 6, 2004Jul 6, 2010Cardiac Pacemakers, Inc.Implantable medical device programming apparatus having a graphical user interface
US7774058Nov 1, 2006Aug 10, 2010Cameron Health, Inc.Anterior positioning on opposing sides of sternum
US7774059Nov 1, 2006Aug 10, 2010Cameron HealthAnterior positioning inactive housing
US7835790Nov 1, 2006Nov 16, 2010Cameron Health, Inc.Anterior active housing subcutaneous positioning methods
US7844322Apr 24, 2006Nov 30, 2010Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US7962203Dec 29, 2003Jun 14, 2011Cardiac Pacemakers, Inc.Arrhythmia display
US7962210May 19, 2009Jun 14, 2011Cardiac Pacemakers, Inc.Implantable medical device with voice responding and recording capacity
US8014862Nov 13, 2010Sep 6, 2011Cameron Health, Inc.Anterior active housing subcutaneous positioning methods
US8046060Nov 14, 2005Oct 25, 2011Cardiac Pacemakers, Inc.Differentiating arrhythmic events having different origins
US8131351Nov 8, 2010Mar 6, 2012Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US8463369Jun 13, 2011Jun 11, 2013Cardiac Pacemakers, Inc.Arrhythmia display
US8548576Mar 2, 2012Oct 1, 2013Cardiac Pacemakers, Inc.System and method for correlation of patient health information and implant device data
US8634917Jul 29, 2008Jan 21, 2014Cardiac Pacemakers, Inc.Method and system for identifying and displaying groups of cardiac arrhythmic episodes
US8706217Mar 30, 2012Apr 22, 2014Cameron HealthCardioverter-defibrillator having a focused shocking area and orientation thereof
Classifications
U.S. Classification607/5, 607/2
International ClassificationA61N1/39
Cooperative ClassificationA61N1/3943
European ClassificationA61N1/39C4B
Legal Events
DateCodeEventDescription
Jul 1, 2005FPAYFee payment
Year of fee payment: 12
Jul 10, 2001FPAYFee payment
Year of fee payment: 8
Jun 25, 1997FPAYFee payment
Year of fee payment: 4
Jan 9, 1995ASAssignment
Owner name: PACESETTER AB, SWEDEN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SIEMENS AKTIENGESELLSCHAFT;REEL/FRAME:007308/0024
Effective date: 19940922
May 21, 1992ASAssignment
Owner name: SIEMENS AKTIENGESELLSCHAFT, A GERMAN CORP.
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:ANDERSEN, HANS;OBEL, MARTIN;WALLEN, LARS;REEL/FRAME:006148/0585;SIGNING DATES FROM 19920507 TO 19920508